1. Field of the Invention
The present invention relates to digital rights management (DRM), and more particularly, to a method of using mobile DRM service in operation with a secure multimedia card (MMC).
2. Description of the Related Art
Recently, digital rights management (DRM) has been actively researched and developed. Commercial services using DRM have already been used or will be used. DRM needs to be used because of the following various characteristics of digital content. Unlike analog data, digital content can be copied without loss and can be easily reused, processed, and distributed, but a large amount of cost, labor, and time are needed to produce the digital content. When the digital content is copied and distributed without permission, a producer of the digital content may lose his/her profit, and his/her enthusiasm for creation may be discouraged. As a result, development of digital content business may be hampered.
There have been several efforts to protect digital content. Conventionally, digital content protection has been concentrated on preventing non-permitted access to digital content, permitting only people who have paid charges to access the digital content. However, when a person who has paid charges intentionally distributes the digital content to other people, these other people can use the digital content without paying charges. To solve this problem, DRM was introduced. In DRM, any one is allowed to freely access encoded digital content, but a license referred to as a rights object is needed to decode and execute the digital content. Accordingly, the digital content can be more effectively protected by using DRM.
A portable storage device is a connectable/disconnectable device such as a portable phone, a computer, or a digital camera which can store data of various types of digital equipment and is portable. The portable storage device includes a storage space for storing data and a portion performing an operation and control. A multimedia card (MMC) is a portable storage device and stores multimedia data to be used for various types of digital equipment, overcoming limitations of conventional hard disks or compact disks. The MMC also includes an operation part that is not included in conventional storage media, thereby having the ability to perform control. As a result, the MMC is suitable to accommodate various kinds of multimedia data in large capacities. Recently, a security function was added to the MMC, thereby developing a secure MMC that secures digital content during storage and transmission and protects copyright. With the development of the secure MMC, rights management on digital content becomes possible in a storage device and digital equipment. Hereinafter, digital equipment such as a digital camera, a portable phone, a computer, and a digital camcorder will be generally referred to as a “device.”
FIG. 1 is a conceptual diagram illustrating license transmission between a secure digital (SD) card 210 and a device 100. The SD card 210, which is one of representative secure memory cards, is not based on mobile DRM service, does not contain an operation for license acquisition while it defines operations between a Content Protection for Recordable Media (CPRM) compatible device and the same. Referring to FIG. 1, the operation of the SD card 210 is defined only in connection with the device 100 but is not defined in connection with a license provider. In other words, a memory card establishes security association with a device through authentication, while the device is able to use the memory card.
FIG. 2 is a conceptual diagram illustrating a license acquisition relationship between a conventional content protection (CP) secure MMC 250 and a license provider 500. The CP secure MMC 250, which is one of representative secure memory cards, is based on memory card DRM service. Thus, it is difficult for the CP secure MMC 250 to be applied to mobile DRM service for a mobile device. Referring to FIG. 2, a secure memory card 250 acquires a license directly from the license provider 500. However, since the CP secure MMC 250 is not equipped with a device for communicating with the license provider 500, it acquires a license from the license provider 500 through a terminal 300, which serves as a communication proxy. There is no security association between the license provider 500 and the terminal 300, or between the terminal 300 and the CP secure MMC 250.
According to this model, the CP secure MMC 250 is directly connected to the license provider 500 to acquire a license, and the license is stored in the CP secure MMC 250. As for CP secure MMC operation, only a memory card can be connected with a license provider. The CP secure MMC 250 is connected to the license provider 500 through the terminal 300, and the CP secure MMC 250 stores the license supplied from the license provider 500.
The conventional memory cards, such as the SD card 100 or the CP secure MMC 250, have a problem in that compatibility with mobile DRM service is not available, making it impossible to be operable with open mobile alliance (OMA) DRM that will be serviced in the near future. Therefore, there exists demand for new secure memory card models compatible with mobile DRM service and implementation methods thereof.
Accordingly, it would be desirable to develop secure memory card models and methods interoperable in a mobile DRM environment, methods in which a memory card can be directly linked to a license provider by mobile DRM service, and methods of operating a memory card as a device of a domain by mobile DRM service.